The present invention relates to a multi-alert radio paging receiver.
An alert means in a conventional radio paging receiver utilizes beeping, flickering of LEDs, or vibration. Along with multifunctions of the radio paging receiver, a multi-address radio paging receiver is proposed. For example, the POCSAG code internationally standardized as the Radio Paging Code No. 1 (RPCl) by the CCIR allows a radio paging receiver to have four paging addresses. Conventionally, for example, when beep or alert signals A, B, C, D, and E correspond to paging addresses, the alert signals A to E are distinguished from each other by changing an ON/OFF duration of a tone having a single frequency f.sub.1, as shown in FIGS. 1(a) to 1(f). When the multi-address radio paging receiver adopts the above method wherein the ON/OFF duration of the tone having a single frequency is changed, the alert signals are complicated, and cannot be easily distinguished from each other.
However, if additional call signals are to be generated by utilizing a tone having another frequency, a difference between the frequencies must be increased to easily distinguish the call signals from each other. A loudspeaker used for the conventional radio paging receiver is usually designed to resonate at a single frequency in order to realize a compact structure and high sound pressure. Therefore, sound pressure is noticeably decreased with respect to the other frequency.